This invention relates to the field of wireless communication systems. More specifically, the present invention relates to a power management system for mobile stations.
The use of wireless communication systems is growing every day with users now numbering well into the millions. Mobile stations, such as handheld telephones, are becoming more portable and easier to use all the time, and mobile station users now rely daily on the availability of wireless systems to accommodate their communication needs. However, the single greatest inconvenience associated with routine use of a mobile station is the constant need to recharge and replace worn down batteries. Even users who make and receive very few telephone calls and operate their mobile stations mostly in the standby mode (awaiting calls) experience the annoying and frequent problem of the mobile station running out of battery power thus becoming dead and useless until the worn battery is replaced with a charged battery. Users demand mobile stations having the longest possible battery life.
A large portion of battery power consumed in standby mode is attributable to call detection processing. For example, in GSM-based wireless communication networks, about once every second a mobile station receives and decodes a full paging message comprising four groups of digital data transmitted at certain time intervals to detect any calls. Only rarely does the detection attempt result in discovery of a telephone call for the mobile station. A great deal of battery power is consumed in this call detection process.
Also, while in standby mode, a mobile station periodically receives and processes transmitted broadcast control data including information about communication parameters (channels, frequencies, communication options, etc.). Existing mobile stations receive and process broadcast control data frequently and without fail, for example every 30 seconds, regardless of whether the information contains anything useful to the mobile station. Again, battery power is consumed by this processing even where the mobile station obtains no new information.
Battery power is even consumed when the mobile station is performing no receiving and processing whatsoever. This is because existing mobile stations use a very high precision master clock that runs continuously. Such master clocks are extremely precise and permit the mobile stations to engage in precisely timed communication as required by many wireless communications standards, and particularly by those such as GSM which depend on time division multiple access wherein mobile stations are allocated very short time periods within which to communicate. The high precision of master clocks comes at a price, however, as such master clocks consume battery power at a much higher rate than clocks having lower precision.
Improvements in battery technology, while helpful, have done little to avoid the seemingly ever-present need to recharge and replace mobile station batteries. What is needed is a system to conserve battery power by minimizing mobile system processing, particularly in standby mode.